SOLVED. 1980s Children's book. [s]

[MR]

When I was in middle school (UK) in the 80s, I had read a series of small stories, about a boy (James, I think) and his adventures with a black cat... I am sure there was a broomstick involved in the stories too, but not necessarily witches...
He would leave from his bedroom window and fly over the roof tops.
I remember them being rather dark, well, they certainly took place at night.
I know it's a little.... OK a lot vague, but any help on this nostalgia would be gratefully appreciated.
Thanks.

[Genesistrine]

Tim and Tobias?

[MR]

Yes yes... James, honestly
Thank you 😘

[Lobstergirl, au gratin]

MR, please add plot details to your topic header. This will help anyone in the future searching for the same book.